This Presentation Consist: Transmission Media & its Classification Topology & it's various classifications

1. COMPUTER NETWORK
Transmission Media & Topology
Presented By:
Sweta Kumari Barnwal
Assistant Professor
Arka Jain University
Jamshedpur, Jharkhand

2. CONTENTS:
 Transmission Media
 Guided
 Un-Guided
 Topology
 Mesh Topology
 Bus Topology
 Star Topology
 Ring Topology
 Tree Topology
 Hybrid Topology

3. TRANMISSIONMEDIA
In data communication terminology, a transmission medium is a
physical path between the transmitter and the receiver i.e it is the
channel through which data is sent from one place to another.
Transmission Media is broadly classified in following manners:

4. GUIDED MEDIA
1. Guided Media:
It is also referred to as Wired or Bounded transmission media. Signals
being transmitted are directed and confined in a narrow pathway by using
physical links. Its features:
 High Speed
 Secure
 Used for comparatively shorter distances
2. Unguided Media:
It is also referred to as Wireless or Unbounded transmission media. No
physical medium is required for the transmission of electromagnetic
signals. Its features:
 Signal is broadcasted through air
 Less Secure
 Used for larger distances

5. GUIDED MEDIA
Twisted-Pair Cables
 It consists of 2 separately insulated conductor wires wound about
each other. Generally, several such pairs are bundled together in a
protective sheath. They are the most widely used Transmission
Media.
 If the pair of wires are not twisted, electromagnetic noises from,
e.g., motors, will affect the closer wire more than the further one,
thereby causing errors.
 It is further divided into two parts
 UTP(Unshielded Twisted Pair)
 STP (Shielded Twisted Pair)

6. GUIDED MEDIA
 Unshielded Twisted Pair (UTP):
This type of cable has the ability to block interference and does
not depend on a physical shield for this purpose. It is used for
telephonic applications.
 Advantages: Least expensive, Easy to install, High speed capacity
 Disadvantages: Susceptible to external interference, Lower
capacity and performance in comparison to STP, Short distance
transmission due to attenuation

7. GUIDED MEDIA
 Shielded Twisted Pair (STP):
This type of cable consists of a special jacket to block external
interference. It is used in fast-data-rate Ethernet and in voice and
data channels of telephone lines.
 Advantages: Better performance at a higher data rate in
comparison to UTP, Eliminates crosstalk, Comparatively faster
 Disadvantages: Comparatively difficult to install and manufacture,
More expensive, Bulky

8. GUIDED MEDIA
Coaxial Cables
It has an outer plastic covering containing 2 parallel conductors each
having a separate insulated protection cover. Coaxial cable transmits
information in two modes: Baseband mode(dedicated cable bandwidth)
and Broadband mode(cable bandwidth is split into separate ranges).
Cable TVs and analog television networks widely used Coaxial cables.
 It carry signalsof higher freq (100KHz–500MHz) than UTPcables
 Outer metallic wrapping servesboth asa shieldagainst noiseand asthe
secondconductorthat completesthe circuit.

9. GUIDED MEDIA
Optical Fibre Cable –
It uses the concept of reflection of light through a core made up
of glass or plastic. The core is surrounded by a less dense glass or
plastic covering called the cladding. It is used for transmission of
large volumes of data.
Advantages: Increased capacity and bandwidth, Light weight,
Less signal attenuation, Immunity to electromagnetic
interference, Resistance to corrosive materials
Disadvantages: Difficult to install and maintain, High cost,
Fragile, unidirectional, there will need another fibre, if we want
bidirectional communication
 Beyond the critical angle  total internal reflection

10. GUIDED MEDIA
Optical Fibre Cable –
An optical fiber consistsof a core(densermaterial) and a
cladding (lessdense material)
 Light bouncesback and forth along the core
 Commonlight sources:LEDsand lasers

11. TRANMISSIONMEDIA
Unguided Media
It is also termed as Wireless or Unbounded transmission media. No
physical medium is required for the transmission of electromagnetic
signals. Its features are:
 Signal is broadcasted through air
 Less Secure
 Used for larger distance
There are 3 major types of Unguided Media:

12. UNGUIDED MEDIA
a) Radiowaves –
These are easy to generate and can penetrate through buildings. The
sending and receiving antennas need not be aligned. Its Frequency
Range is 3KHz – 1GHz. AM and FM radios and cordless phones use
Radiowaves for transmission.
Further Categorized as (i) Terrestrial and (ii) Satellite.
b) Microwaves –
It is a line of sight transmission i.e. the sending and receiving
antennas need to be properly aligned with each other. The distance
covered by the signal is directly proportional to the height of the
antenna. Its Frequency Range is1GHz – 300GHz. These are majorly
used for mobile phone communication and television distribution.
c) Infrared –
Infrared waves are used for very short distance communication. They
cannot penetrate through obstacles because of low wavelength. This
prevents interference between systems. Frequency Range:300GHz –
400THz. It is used in TV remotes, wireless mouse, keyboard, printer,
etc.

13. TOPOLOGY
The Graphical arrangement of a network which comprises of nodes
and connecting lines between sender and receiver is referred as
network topology. The various network topologies are:
Mesh
Bus
Star
Ring
Tree
Hybrid

14. TOPOLOGY
Mesh Topology:
In this every device is connected to another device.
 If suppose, N number of devices are connected with each other in
mesh topology, then total number of ports that is required by each
device is ? N-1. In the Figure 1, there are 5 devices connected to
each other, hence total number of ports required is 4.
 If suppose, N number of devices are connected with each other in
mesh topology, then total number of dedicated links required to
connect them is N(N-1)/2.
 Advantages: It is robust, Fault is diagnosed easily. Data is reliable
because data is transferred among the devices through dedicated
channels or links., Provides security and privacy.
 Disadvantages: Installation and configuration is difficult, Cost of
cables are high as bulk wiring is required, hence suitable for less
number of devices, Cost of maintenance is high.

15. TOPOLOGY
Star Topology :
In this every device is connected via Central Unit/Hub.
 In this all the devices are connected to a single hub through a
cable. This hub is the central node and all others nodes are
connected to the central node. The hub can be Passive (not
intelligent) or Active (intelligent) in nature.
 Advantages : If N devices are connected to each other in star
topology, then the number of cables required to connect them is N.
So, it is easy to set up, Each device require only 1 port i.e. to
connect to the hub.
 Disadvantages: If the concentrator (hub) on which the whole
topology relies fails, the whole system will crash down, Cost of
installation is high, Performance is based on the single
concentrator i.e. hub.

16. TOPOLOGY
Bus Topology :
In this every computer and network device is connected to single
cable.
 It transmits the data from one end to another in single direction.
No bi-directional feature is in bus topology.
 Advantages: If N devices are connected to each other in bus
topology, then the number of cables required to connect them is 1
?which is known as backbone cable and N drop lines are required,
Cost of the cable is less as compared to other topology, but it is
used to built small networks.
 Disadvantages: If the common cable fails, then the whole system
will crash down, If the network traffic is heavy, it increases
collisions in the network. To avoid this, various protocols are used
in MAC layer known as Pure Aloha, Slotted Aloha, CSMA/CD
etc.

17. TOPOLOGY
Ring Topology:
It forms a ring connecting a devices with its exactly two neighboring
devices.
The following operations takes place in ring topology are :
 One station is known as monitor station which takes all the
responsibility to perform the operations.
 To transmit the data, station has to hold the token. After the
transmission is done, the token is to be released for other stations
to use.
 When no station is transmitting the data, then the token will
circulate in the ring.
 Advantages :The possibility of collision is minimum in this type
of topology, Cheap to install and expand.
 Disadvantages: Troubleshooting is difficult in this topology,
Addition of stations in between or removal of stations can disturb
the whole topology.

18. TOPOLOGY
Tree Topology:
This topology have hierarchical flow of data.
 Data flow occurs from top to bottom i.e from the central hub to
secondary and then to the devices or from bottom to top i.e.
devices to secondary hub and then to the central hub.
 Advantages : It allows more devices to be attached to a single
central hub thus it increases the distance that is travel by the signal
to come to the devices, It allows the network to get isolate and
also prioritize from different computers.
 Disadvantages: If the central hub gets fails the entire system fails,
The cost is high because of cabling.

19. TOPOLOGY
Hybrid Topology:
It is a collection of two or more topologies which are described
above.
 This is a scalable topology which can be expanded easily. It is
reliable one but at the same it is a costly topology.
 It is a combination of two or more same kind or different kind of
topologies. That's why it will consist the advantages and
disadvantages of respective topologies.

20. THANK YOU